Transporting device, in particular for transporting sheet-like substrates through a coating installation

ABSTRACT

A transport device and method of transporting a substrate using a rotatable shaft and baffles may be used to extend cleaning intervals for the transport device and reduce deposition of a vapour deposition material upon the transport device.

The invention relates to a transporting device, in particular fortransporting sheet-like substrates through a coating installation.

BACKGROUND

For transporting substrates through coating installations, various typesof transporting devices are known. Such transporting devices oftencomprise a plurality of transporting rollers.

SUMMARY

A transporting device for transporting sheet-like substrates through acoating installation, can include transporting rollers rotatably mountedon both sides and horizontally arranged transversely in relation to atransporting direction, the rollers having uppermost surface linesdefining a transporting plane, the rollers having end parts that have asmaller diameter than the middle part of the transporting rollers.

In one aspect, a transporting device can include a roller that isprotected by a shield or baffles. The baffles configured to be mounteddisplaceably in an axial direction of the transporting rollers between afirst position and a second position, the baffles arranged between theend parts of the transporting rollers and the transporting plane. Ashield can have the form of a collector ribbon, a parallel foil loop, atransverse foil loop, a roll-to-roll cassette, or a rotatable horizontaldisc. A roller can also contain a heating element to minimize depositionon the roller.

In another aspect, a transporting device can include a back-up roller.The back-up roller can be configured to support a roller such as abridge roller. The back-up roller can be positioned in a lower regionand the roller can be positioned on a surface region. So long as thediameter of a back-up roller remains largely unchanged, the surfacespeed of the bridge roller can remain fixed, thereby maintaining theefficiency of the system. A back-up roller can include a guidanceelement. An on-axis guide pin can also fix the axial position of thebridge roller if the bridge roller is solid, or has an end cap, forexample.

In yet another aspect, a method for transporting a sheet-like substratesheet through a coating installation using the transporting deviceincludes introducing a material and a carrier gas into a first chamberincluding the transporting device, heating the material such that aportion of the material vaporizes into a vapor, directing a mixture ofthe vapor and carrier gas through a second chamber to form asubstantially uniform vapor/carrier gas composition, directing thesubstantially uniform vapor/carrier gas composition toward a surface ofa substrate having a temperature lower than the vapor. The shield orbaffle is arranged proximate to a vapor distributor to capture strayflux.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary embodiment of the invention in several views,

FIG. 2 shows a sectional representation of a transporting roller withtwo baffles and

FIG. 3 shows a partial view of the transporting system according to theinvention.

DETAILED DESCRIPTION

A transporting roller or a plurality of transporting rollers arearranged transversely in relation to a transporting direction ofsheet-like substrates and on which the substrates are transportedthrough the coating installation, the transporting rollers rotating. Theuppermost surface lines of the transporting rollers, i.e. the lines inwhich the substrates are in contact with the transporting rollers,define the transporting plane. In this case, some or all of thetransporting rollers are driven by drive means provided for the purpose.Such transporting devices extend through the entire coatinginstallation, i.e. both through those regions of the coatinginstallation that serve for the coating of the substrates and throughother regions that are necessary for the process, for example transferchambers, evacuation chambers, etc.

To achieve a uniform coating rate over the width of the substrate, anoverhang of the coating source beyond the width of the substrate isrequired on both sides. Typical overhangs are of the order of magnitudeof 10% and more on each of both sides, the coating rate outside thesubstrate zone falling with increasing distance from the edge of thesubstrate, at first slightly and finally exponentially.

In particular at high coating rates, and especially whenever linearsources are concerned, as are typical for vaporizing processes, andafter long process times, the regions of the transporting rollers lyingoutside the substrate region are coated if no countermeasures are taken.

The layers building up on the transporting rollers inside and outsidethe substrate region lead to uneven support of the substrates on thetransporting rollers, so that in the end transporting problems occur. Inparticular at high coating rates, the transporting rollers must becleaned after relatively short process times, which greatly restrict theavailability of the installation, since cooling and vacuum and thermalconditioning take up considerable times.

Stationary baffles that keep the undesired layers of stray vapour awayfrom the transporting rollers fail if the layers that have built up inthe region of the edges of the substrate can, because of theirthickness, partially block the vapour stream and consequently adverselyinfluence the homogeneity of the layer thicknesses. This has the effectthat the undesired layers of stray vapour must be continuouslytransported away, for instance by movable baffles, belts running next tothe substrate or similar devices.

The object of the present invention is therefore to provide atransporting device of the type mentioned with which the intervalsbetween necessary cleaning work on account of undesired vapourdeposition on the transporting rollers are longer than in the case ofconventional transporting devices.

The transporting device according to the invention, in particular fortransporting sheet-like substrates through a coating installation,comprises transporting rollers which are rotatably mounted on both sidesand horizontally arranged transversely in relation to the transportingdirection, the uppermost surface lines of the transporting rollersdefining the transporting plane, and is characterized in that the endparts of the transporting rollers have a smaller diameter than themiddle part of the transporting rollers and in that baffles which aremounted displaceably in the axial direction of the transporting rollersbetween a first position and a second position are arranged between theend parts of the transporting rollers and the transporting plane.

The length of the middle part is in this case chosen such that it isless than the width of the substrates to be transported, so that thesubstrates protrude beyond the middle part of the transporting rollers.This prevents unwanted vapour from being deposited on the middle part.The end parts of the transporting rollers have a smaller diameter thanthe middle part and in this way create the installation space that isrequired to attach baffles which reach to below the edges of thesubstrate and guard the end parts of the transporting rollers againstunwanted vapour deposition.

The fact that the baffles are mounted in an axially displaceable mannerhas the effect of considerably extending the cleaning intervals of thetransporting device. At first the baffles are arranged in a firstposition, in which the end of the baffle lies underneath the substrateand, in the horizontal direction, as close as possible to the middle ofthe transporting roller. Vapour-depositing material that gets beyond theedge of the substrate hits the baffle.

During operation of the transporting device, the baffles arecontinuously displaced from the middle part to the ends of thetransporting rollers. As a result, the increase in thickness of thelayer produced on the baffles is limited, since the vapour keeps hittingnew portions of the baffle. The second position of the baffle is reachedshortly before the end of the baffle is drawn up under the substrate.Since, if the baffle were drawn out any further, vapour would bedeposited on the end part of the transporting roller, the displacementof the baffle is stopped at this point and cleaning of the baffle isperformed.

The baffle may be configured for example as a planar or curved metalsheet, but also as a hollow-cylindrical shielding sleeve, for example asa thin-walled tube.

In one refinement of the invention, rotatably mounted supporting rollersare provided underneath the transporting rollers, arranged in a parallelplane lying underneath the transporting plane.

The supporting rollers give the transporting rollers a third, centralsupporting region, which prevents unwanted deformation of thetransporting rollers under the load of the substrate and so allow theuse of transporting rollers with a relatively small diameter, wherebythe transporting device has a low weight and can be produced at lowcost.

In a further refinement of the invention, the middle part of thetransporting rollers has at least one annular indentation, which isarranged in the end face and the outside diameter of which is less thanthe outside diameter of the middle part.

To make the cleaning interval as long as possible, the decisive factoris that the first and second positions of the baffles are as far apartfrom each other as possible, i.e. that the baffles can be displaced byan amount that is as long as possible. One possibility could be to makethe middle part of the transporting rollers much shorter than thesubstrates are wide. However, this entails the risk of the substratesbeing deformed under the dead weight of their regions protruding beyondthe middle part of the transporting rollers.

It is therefore advantageous to provide an annular indentation in theaxial direction in the end face of the middle part of the transportingroller, i.e. between the circumferential surface of the end part and thecircumferential surface of the middle part, with the effect that, whenthere is a slight overhang of the substrates beyond the middle part, itnevertheless allows the baffle to be slid relatively far under thesubstrate into the first position. A hollow-cylindrically formed baffleis especially suitable for this in particular. Therefore,hollow-cylindrically formed baffles represent a particularlyadvantageous refinement of the invention.

In a further refinement of the invention, the baffles are produced fromflexible material. For example, the baffle may be formed as a flexibletube which can be compressed or extended in the longitudinal direction,in the case of which the axial displacement of the baffle substantiallytakes place by displacement of the end of the flexible tube that isunder the substrate from a first position to a second position, so thatnew regions of the baffle are exposed to the vapour deposition.

In a further refinement of the invention, the inside diameter of theindentation corresponds substantially to the outside diameter of the endpart of the transporting roller.

If the inside diameter of the indentation and the outside diameter ofthe end part of the transporting roller deviate significantly from eachother, the insertion and displacement of the baffle in the indentationcan lead to problems. It is therefore advantageous to produce a smoothtransition from the circumferential surface of the end part to theinside diameter of the indentation.

To achieve this in a simple way, instead of producing the transportingroller from solid material on a lathe, the transporting roller accordingto the invention may also be produced from a shaft of constant diameterand a hollow-cylindrical transporting sleeve that is concentricallyarranged, slipped over the shaft and preferably securely connected tothe shaft in its middle region. In this case, the transporting sleevesform the middle part of the transporting rollers, while the free ends ofthe shaft represent the end parts of the transporting rollers.

In a further refinement of the invention, annular indentations areprovided on both end faces of the middle part, their total depth beingless than the length of the middle part.

This embodiment corresponds geometrically to the transporting rollerexplained above that is made up of a shaft and a hollow-cylindricaltransporting sleeve. It is evident from this that the way in which thetransporting rollers are produced has no influence on the functionalcapability of the invention. The advantage of this refinement is thatbaffles for which the first positions lie close together can be arrangedon both sides, so that a great distance is available for thedisplacement of the baffles.

In a further refinement of the invention, at least one actuating deviceis also provided, for displacing the baffles.

The actuating device advantageously comprises at least one yoke,connected to at least one baffle, and at least one tie rod, connected tothe yoke.

In a further refinement of the invention, a drive means is alsoprovided, for driving the transporting rollers and/or for displacing thebaffles.

Transporting devices for coating installations are usually provided inany case with a drive means for driving the transporting rollers. It istherefore particularly advantageous to use this drive means also fordisplacing the baffles.

The drive means is advantageously a geared motor. Geared motors arecapable of accomplishing relatively low speeds of movement. In addition,it is possible to provide the geared motor with two outputs, whichoperate at different speeds. In this way, or else by interposing anadditional gear mechanism, the displacement of the baffles can takeplace proportionally to the rotation of the transporting rollers, sothat the baffles are only displaced when the transporting rollersrotate.

Referring to FIG. 1, an exemplary embodiment of the invention isrepresented in several views, in which embodiment the transportingdevice according to the invention comprises a number of transportingrollers, which are arranged in a horizontal plane transversely inrelation to the transporting direction of the substrates in a coatinginstallation.

The transporting device in the coating region is constructedsubstantially as follows. The vapour source is located over thesubstrate, transversely in relation to the transporting direction, fromwhich source the vapour stream emerges in the direction of the substratelying under it. To the left and right of the vapour source there aretransporting rollers 1, which comprise a shaft 11 and a transportingsleeve 12. The diameter of the transporting sleeves 12 should be chosento be as large as possible, for reasons still to be explained below. Thetransporting sleeves 12 have the form of tubes. Their length is slightlyless than the width of the substrate, so that the substrates overhang onboth sides of the transporting sleeves 12. This firstly ensures that thetransporting sleeves 12 cannot be coated on their circumferentialsurfaces, apart from a slight coating of the transporting sleeves 12 onaccount of the unavoidable gaps in the case of coating individualsubstrates.

The transporting sleeves 12 are each driven by a concentric,water-cooled shaft 11 of small diameter. The water cooling may beomitted if the process temperature is so low that critical overheatingof the components cannot occur. The shaft 11 has the function especiallyof driving the transporting sleeve 12. The mounting of the transportingshaft 1 takes place primarily by the supporting rollers 2 arranged underit. The supporting roller 2 may be omitted if the width of thesubstrate, and consequently the width of the shaft 11, is small andconsequently mechanical support is not absolutely necessary.

The connection of the transporting sleeve 12 to the shaft 11 only takesplace in the middle. On the shaft 11 there are movable baffles 3 on bothsides in the form of hollow-cylindrical shielding sleeves, whichrespectively extend almost up to the middle in the transporting sleeve12 and are dimensioned in their length in such a way that they enclosethe shaft 11 up to the process chamber wall. The undesired stray vapouroutside the substrate region is deposited on the movable baffles 3primarily in the direct proximity of the transporting roller 1, wherebythe diameter of the baffles 3 increases considerably, depending on thecoating rate. Continuous or discontinuous drawing out of the movablebaffles 3 on both sides allows the layers of stray vapour to betransported out from the coating region, so that the servicing intervalscan be extended considerably.

The amount of condensed stray vapour that can be transported out fromthe coating zone depends on the diameter of the transporting sleeve 12,the diameter of the shaft 11 and the length of the baffle 3.

Further extension of the operating time is possible by replacing thecoated baffle 3 with an uncoated one. The change can be made through asuitably formed vacuum lock, so that an interruption of the vacuum isnot necessary.

In FIG. 2, a transporting roller 1 of a transporting device arranged ina coating installation is represented in section. The transportingroller 1 comprises a shaft 11 and a transporting sleeve 12. The freeends of the shaft 11 form the end parts of the transporting roller 1.The transporting sleeve 12 is connected centrally and concentrically tothe shaft 11 and forms the middle part of the transporting roller 1. Oneach of the two end faces, the transporting sleeve has an annularindentation 13, the inside diameter of which is, identical to theoutside diameter of the shaft 11. A baffle 3 is pushed into eachindentation 13 and located there in a first position.

During the operation of the transporting device, the transporting roller1 rotates and in this way conveys the substrate, which rests on thetransporting sleeve 12, through the coating installation. At the sametime, the baffle 3 is slowly and continuously drawn out from theindentation 13, i.e. displaced in the axial direction of thetransporting roller 1. The displacement is ended when the baffle 3reaches its second position. In this second position, the end of thebaffle 3 is still located underneath the substrate resting on thetransporting sleeve 12, so that vapour is not deposited on the shaft 11.

In FIG. 3, a number of transporting rollers 1 belonging to atransporting device arranged in a coating installation are represented.

The ends of the sleeves 3 facing away from the chamber wall of thecoating installation have a double flange 31. Also provided is anactuating device, which has a yoke 41, two tie rods 42, two gearmechanisms 43 and a drive shaft 44. The yoke 41 engages in the doubleflanges 31 of four baffles 3. Two tie rods 42 are connected to the yoke41 and each protrude into a guide sleeve 51, which is connected to thechamber wall 52 of the coating installation and widens the interiorspace of the coating installation, so that the tie rods 42 are disposedin the vacuum.

Arranged on the guide sleeves 51 are gear mechanisms 43, which are inoperative connection with the tie rods 42 and are connected by a driveshaft 44 to one another and to a geared motor (not represented). As aresult, a movement is transmitted from the geared motor via the driveshaft 44 to the gear mechanism 43, from the latter to the tie rods 42,the yoke 41 and finally from the yoke 41 to the baffles 3, so that thebaffles 3 are displaced from their first position into their secondposition when the transporting device is in operation.

A method for transporting a sheet-like substrate sheet through a coatinginstallation includes introducing a material and a carrier gas into afirst chamber, heating the material such that a portion of the materialvaporizes into a vapor, directing a mixture of the vapor and carrier gasthrough a second chamber to form a substantially uniform vapor/carriergas composition, directing the substantially uniform vapor/carrier gascomposition toward a surface of a substrate having a temperature lowerthan the vapor, such that the vapor condenses on the substrate as a filmhaving substantially uniform thickness and crystallization, providing atleast one roller to convey a sheet-like substrate along a transportingdirection, providing at least one roller to have an end that has asmaller diameter than the middle of the roller, and arranging at leastone shield proximate to a vapor distributor to capture stray flux.

For example, a method for transporting a sheet-like substrate caninclude introducing vapors of cadmium and tellurium into a containedenvironment and conveying a sheet-like substrate including a planarglass sheet heated to a temperature in the range of about 550 degrees to640 degrees C. within the contained environment for continuous elevatedtemperature deposition of a layer of cadmium telluride onto one surfaceof the substrate to function as a semiconductor for absorbing solarenergy. The sheet-like substrate can be oriented horizontally within thecontained environment with the one surface of the substrate facingupwardly for the deposition of the cadmium telluride thereon and withthe other surface of the substrate facing downwardly and being supportedwithin the periphery thereof for horizontal conveyance while maintainingthe planarity of the glass sheet.

Continuous processing of thin films onto glass sheet substrates isdisclosed by U.S. Pat. No. 5,248,349, U.S. Pat. No. 5,372,646, U.S. Pat.No. 5,470,397, and U.S. Pat. No. 5,536,333. The vapor depositionutilized to provide the continuous coating can be performed within anoven that defines a heated chamber and that is located within anenclosure. A roll conveyor can include rolls that extend through theoven to support a glass sheet substrate on which the coating isperformed and a drive mechanism located internally of the enclosure butexternally of the oven drives the ends of the conveyor rolls whichproject outwardly from the oven. Also, U.S. Pat. No. 5,945,163, U.S.Pat. No. 6,037,241, and U.S. Pat. No. 6,719,848 disclose an apparatusand method for performing chemical vapor deposition wherein the gaseousmaterial to be deposited is passed through a heated permeable membranefrom a material supply for deposition on the substrate.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

LIST OF REFERENCE NUMERALS

1 transporting roller

11 shaft

12 transporting sleeve

13 indentation

2 supporting roller

3 baffle

31 double flange

41 yoke

42 tie rod

43 gear mechanism

44 drive shaft

51 guide sleeve

52 chamber wall

1-14. (canceled)
 15. A transport device comprising: a rotatable shaft with a longitudinal axis; a transporting sleeve configured to rotate with the rotatable shaft; a first indentation formed on a first end of the transporting sleeve; a second indentation formed on a second end of the transporting sleeve; a first baffle, axially movable along the rotatable shaft, sized to fit about the rotatable shaft and within the first indentation; and a second baffle, axially movable along the rotatable shaft, sized to fit about the rotatable shaft and within the second indentation.
 16. The transport device of claim 15, further comprising a mechanism for moving the first and second baffles along the longitudinal axis.
 17. The transport device of claim 15, further comprising a rotatable supporting roller configured to support the rotatable shaft.
 18. The transport device of claim 15, wherein the inside diameter of the first indentation corresponds substantially to the outside diameter of the rotatable shaft.
 19. The transport device of claim 15, wherein the first and second baffles are formed from flexible material.
 20. The transport device of claim 16, wherein the mechanism for moving the first and second baffles along the longitudinal axis comprises a first yoke connected to the first baffle and a first tie rod connected to the first yoke.
 21. The transport device of claim 15, further comprising a drive structure means configured to rotate the rotatable shaft.
 22. The transport device of claim 21, wherein the drive structure means is a geared motor.
 23. The transport device of claim 16, wherein the mechanism for moving the first and second baffles is configured to displace the first and second baffles proportional to the rotation of the rotatable shaft.
 24. The transport device of claim 15, wherein the transporting sleeve comprises an axial length, wherein the axial length is less than a width of a transported substrate.
 25. The transport device of claim 20, wherein the first baffle comprises a first flange and the first yoke is configured to engage the first flange.
 26. The transport device of claim 25, wherein the tie rod is connected to a drive mechanism.
 27. The transport device of claim 15, wherein the shaft is water-cooled.
 28. The transport device of claim 21, wherein the drive structure means is configured to displace the first and second baffles.
 29. The transport device of claim 21, further comprising a second drive structure means configured to displace the first and second baffles.
 30. The transport device of claim 15, wherein the rotatable shaft comprises an outer diameter and the transporting sleeve comprises a first inner diameter and a second inner diameter, wherein the first inner diameter is substantially the same as the outer diameter and the second inner diameter is substantially greater than the outer diameter.
 31. The transport device of claim 15, wherein the transport device is configured to operate in a substantial vacuum and at temperatures in the range of 550° C. to 640° C.
 32. The transport device of claim 15, wherein a transported substrate is configured to be provided between the transporting sleeve and a vapour source.
 33. The transport device of claim 15, further comprising: a plurality of rotatable shafts, each with a respective longitudinal axis; a plurality of transporting sleeves, each configured to rotate with a respective rotatable shaft; a first indentation formed on a first end of each transporting sleeve; a second indentation formed on a second end of each transporting sleeve; and a first baffle and second baffle provided on each rotatable shaft of the plurality of rotatable shafts, axially movable along the respective rotatable shaft, sized to fit about the respective rotatable shaft, wherein each first baffle is sized to fit within a respective first indentation and each second baffle is sized to fit within a respective second indentation.
 34. A method of transporting a substrate comprising: rotating a rotatable shaft, wherein the rotatable shaft rotates a transporting sleeve; moving a first baffle longitudinally along the rotatable shaft, wherein the first baffle is sized to fit partially within a first indention formed on a first end of the transporting sleeve; and moving a second baffle longitudinally along the rotatable shaft, wherein the second baffle is configured to fit within the second indention. 